The invention relates to a vehicular steering wheel capable of being evenly heated.
It has long been considered desirable to have a heating system for the vehicular steering wheel.
During cold weather while a vehicle is not in operation, a vehicular steering wheel can become bitterly cold. When an operator of a vehicle initially grasps the steering wheel, he may experience discomfort, and this discomfort can persist until the steering wheel warms up. The discomfort can cause a lapse in the operator""s concentration and could potentially adversely affect his driving performance. For individuals suffering from arthritis and other diseases of the hand, the discomfort from the cold steering wheel can be acute. Even after the vehicle itself has reached a comfortable temperature, the steering wheel usually remains cold to the touch and might require the use of gloves by the driver. For the above-mentioned reasons, there has been a desire to develop a means to rapidly increase the temperature of a vehicle steering wheel.
There have been a number of proposals for this steering wheel problem such as the use of hot air, heated coolants, and electric resistance (resistance wire technology). The use of resistance wire technology became the most popular method of tackling this problem. This method achieved the goal of warming a steering wheel by using lengths of resistance wire as heating elements. The wire was embedded within the steering wheel and the passage of electrical current through the wire would generate heat. Thus the popularity of this method stemmed from its simplicity and reliability. An advantage of using resistance wire is the flexible installation possibilities; however, the major drawback to this technology is that the steering wheel does not uniformly increase in temperature. Use of resistance wire would create areas or zones on the steering wheel that was cold to the touch and areas or zones that were warm to the touch. Also, the resistance wire is much easier to be damaged, once the wire is broken at any place along the steering wheel rim, the wheel will no longer be able to be heated.
Noda et al., U.S. Pat. No. 4,640,340, teaches an apparatus for heating and cooling a steering wheel. In Noda et al., the thermoelectric transducers are responsible for generating or absorbing heat. The thermoelectric transducer either generates heat or absorbs heat depending on which direction the electric current flows. The thermoelectric transducers are situated below a conductive plate, which is situated underneath the skin layer.
Lorenzen et al., U.S. Pat. No. 5,847,360, teaches an electric steering wheel heating element mounting on top of a steering wheel rim. The heating element is made of three electrically conductive segments: one linear segment and two curved adjacent segments.
Haag et al., U.S. Pat. No. 6,093,908, teaches a heated steering wheel having a heating element made from a carbon fiber woven material. The heating element has the unique property of a negative temperature coefficient.
The object of this invention is to provide a steering wheel that is capable of being uniformly heated. According the present invention the heated steering wheel comprises an armature, a substrate, a heating element, a foam layer, and a leather wrapping. The heating element in the present invention is a thin fabric woven made from nylon coated with silver. The foam layer is positioned around the heating element and is made from a material that is substantially conductive so that heat generated from the heating element can reach the surface of the steering wheel rim. The foam layer is included in the heated steering wheel to conceal the presence of the bus bar.
It is a further object of this invention to provide such heated steering wheel, which is durable and can withstand the stress and strain placed on the steering wheel by the driver during the operation of the vehicle.